Semiconductor devices are manufactured or fabricated on semiconductor wafers using a number of different processing steps to create transistor and interconnection elements. To electrically connect transistor terminals associated with the semiconductor wafer, conductive (e.g., metal) trenches, vias, and the like are formed in dielectric materials as part of the semiconductor device. The trenches and vias couple electrical signals and power between transistors, internal circuit of the semiconductor devices, and circuits external to the semiconductor device.
In forming the interconnection elements the semiconductor wafer may undergo, for example, masking, etching, and deposition processes to form the desired electronic circuitry of the semiconductor devices. In particular, multiple masking and plasma etching step can be performed to form a pattern of recessed areas in a dielectric layer on a semiconductor wafer that serve as trenches and vias for the interconnections. In order to removal particles and contaminations in trench and via post etching or photo resist ashing, a wet cleaning step is necessary. Especially, when device manufacture node migrating to 65 nm and beyond, the side wall loss in trench and via during is crucial for maintaining the critical dimension. In order to reduce or eliminating the side wall loss, it is important to use moderate, dilute chemicals, or sometime de-ionized wafer only. However, the dilute chemical or de-ionized water usually is not efficient to remove particle in the trench and via. Therefore the mechanical force such as ultra sonic or mega sonic is needed in order to remove those particles efficiently. Ultra sonic and mega sonic wave will apply mechanical force to wafer structure such as trenches and vias, the power intensity and power distribution is key parameters to control the mechanical force within the damage limit and at same time efficiently to remove the particles.
Mega sonic energy coupled with nozzle to clean semiconductor wafer is disclosed in U.S. Pat. No. 4,326,553. The fluid is pressurized and mega sonic energy is applied to the fluid by a mega sonic transducer. The nozzle is shaped to provide a ribbon-like jet of cleaning fluid vibrating at mega sonic frequencies for the impingement on the surface.
A source of energy vibrates an elongated probe which transmits the acoustic energy into the fluid is disclosed in U.S. Pat. No. 6,039,059. In one arrangement, fluid is sprayed onto both sides of a wafer while a probe is positioned close to an upper side. In another arrangement, a short probe is positioned with its end surface close to the surface, and the probe is moved over the surface as wafer rotates.
A source of energy vibrates a rod which rotates around it axis parallel to wafer surface is disclosed in U.S. Pat. No. 6,843,257 B2. The rod surface is etched to curve groves, such as spiral groove. It is needed to have a better cleaning method for cleaning particles and contamination on surface of wafer or substrate with higher efficiency and lower mechanical damages.